Effects of S-PRG Powder on Dentinal Tubule Occlusion in vitro

Objectives: Clinically, there is no quite reliable treatment for dentin hypersensitivity until today. Many reports have suggested that the occlusion of dentinal tubules cause decreases of sensitivity in dentin. Additionally, it is recommended that dentin tubules should be occluded without leading to demineralization of the surface. The aim of this study was to evaluate the effect of novel fluoride-releasing medicament using surface pre-reacted glass-ionomer (S-PRG) powder on the dentinal tubule occlusion by SEM. Methods: 24 bovine dentin specimens were prepared to the sizes of 3x5mm and divided into four groups (n=4). We used following materials as the components of novel medicament system i.e. S-PRG powder (average particle size of 0.8µm) and fumed silica (average particle size of 12nm), and 6.5, 9.75 and 13.75w/v% polyacrylic acid. The dentin surface simulating hypersensitive dentin was treated with a mixture of S-PRG powder and polyacrylic acid for 15seconds with scrubbing. And then, they were immersed in deionized water for 24hrs. The control group was untreated. SEM observation was carried out to evaluate whether the deposits by the novel treatment occluded in the dentinal tubules. Results: The surfaces of the specimens treated with the novel medicament system using 6.5 or 9.75w/v % polyacrylic acid were completely covered with fine deposits, and the dentinal tubules were occluded with fine deposits to a depth of 12–15µm. On the other hand, the specimens treated using 13.75w/v% polyacrylic acid were only covered with fine deposits to a depth of 1–2µm. Conclusions: We can conclude that this newly developed fluoride-releasing system for dentinal tubule occlusion should be not only effective for dentin hypersensitivity, but also these fine deposits might contribute to occlude dentinal tubules together with dentinal fluid continuously.